ROCHELLE — Nippon Sharyo USA this morning celebrated the completion of its rail car manufacturing plant in Rochelle and announced it will hire an additional 90 employees, bringing total employment to nearly 500.

Illinois Gov. Pat Quinn was among the dignitaries attending to celebrate one of the most significant new operations to be built in the Rock River Valley in decades.

Nippon Sharyo is based in Aichi, Japan. Its U.S. subsidiary is based in Arlington Heights. Launched in 1896, the company makes trains and other transportation equipment such as railway freight cars, light rail vehicles, and subway trains. Its other two divisions make construction and industrial equipment and steel structures such as bridges.

In October 2010, the company announced it would build a 465,000-square-foot plant in Rochelle near Interstates 39 and 88 for a plant that would build 120 passenger rail cars a year.

The announcement was a shot in the arm to Rochelle and the region as a whole. In October 2010, the unemployment rate in Ogle County was 11.8 percent. Company officials originally said the plant would employ 300. The company began hiring in earnest in June 2012 and launched production a month ago.

But since construction began, Nippon Sharyo has landed several large contracts, including a $352 million contract for rail cars from the California Department of Transportation. Nippon Sharyo already employs 400 in Rochelle and the additional 90 workers will make it Ogle County’s third-largest employer behind just the Exelon nuclear generating station and Rochelle Foods.

“This was a huge, huge win for Rochelle,” said John Lewis, a retired Northern Illinois University economist who now runs a consulting firm. “Most communities struggle to hold on to the manufacturing jobs they have. It is really rare in today’s economy to land a new plant creating hundreds of new jobs.”

Lewis estimates every job created at Nippon Sharyo will create three more in its supply chain. Ogle County’s jobless rate already had fallen to 7.9 percent in June. Winnebago County’s jobless rate was 8.9 percent in June and Boone’s rate was 8.5 percent.

In terms of economic impact for the region, the rail car plant ranks on the same level as the new Loves Park manufacturing campus being built by Woodward Inc., which will create more than 600 new jobs over five years, and the Belvidere expansion of the Chrysler Group LLC plant that boosted employment there to a record 4,500 people.